When most railfans think of ALCo diesel cab
units, the PA and, to a lesser degree, the FA series, immediately
come to mind. However, the PA, introduced in 1946, was not the
first streamlined cab unit produced by ALCo. In 1940, ALCo introduced
the prototype of the DL-109, designated the DL103b. The prototype
unit was purchased by the Chicago, Rock Island, and Pacific, and
differed from subsequent DL units primarily in type of prime mover
and electrical systems. The DL-109's streamline styling was designed
by noted industrial designer Otto Kuhler, who had designed the
shrouding for some of the U.S.'s most famous streamlined steam
locomotives. The DL-109's styling was not significantly different
from it's contemporaries being produced by EMD; it featured the
high cab, rounded tapering nose, and sloping windshields found
in the EMD cab units of the time. The DL-109's most distinctive
feature was probably the three-panel windshield design not found
on any other cab units. In addition, variations in headlight assemblies
could be found among the DL-109's various owners. A total of 74
DL-109 cab units and 4 booster units (designated DL-110) were
produced from 1940 to 1945. The New Haven was principal purchaser
of the DL-109, owning 60 of the Units. Other roads to purchase
the DL-109 included the Chicago & Northwestern (1 Unit), Gulf,
Mobile & Ohio (3 Units), Milwaukee Road (2 Units), Rock Island
(4 Units), Santa Fe (2 Units), Southern (6 Units). Even with the
limits placed on ALCo passenger locomotive production during the
Second World War, New Haven was allowed by the War Production
Board to acquire 60 DL-109's because it utilized them as dual
service locomotives.

Technical data: Model: DL-109

Wheel configuration: A1A-A1A

Length: 74 feet, six inches

Horsepower: 2000

Engine: Each unit was powered by two 1000 horsepower,
six cylinder Model 539 diesel engines. The prototype unit, which
was purchased by the Rock Island, had a turbo-charged Model 538
engine and was actually designated as DL-103b. ALCo dropped this
powerplant in favor of the Model 539, which was adopted for all
subsequent DL-109 production. Although replaced by the 16 cylinder,
2000 horsepower, turbo-charged Model 244 prime mover in the ALCo
PA series, the Model 539 was still being installed in mixed traffic
locomotives as late as 1957.

Produced: 1940-45 Units sold: 78 (74 cab units,
4 boosters)

Survivors: No known survivors

Historical Analysis:

While certainly not as well known as the ALCo
cab units which followed it, and not built in the numbers EMD
cab units were, the DL-109 has its place in the pantheon of exotic
diesel cab units. With the conclusion of the Second World War
in 1945, the DL-109's were worn out from heavy war-time usage.
ALCo was ready to introduce its new passenger diesel design, the
PA series, and the DL-109 was relegated to the distant memories
of railfans. Had it not been for the wartime restrictions on passenger
locomotive development and production, one can speculate that
DL-109's would have been produced in much higher numbers than
they were. In fact, had it not been for the War Production Board
granting an exemption to the New Haven in order to acquire DL-109's,
it would have an even more obscure history among diesel cab units.

By the time the war ended, it was becoming
more evident that the diesel locomotives would one day replace
steam technology. ALCo had a new serious competitor in EMD, and
the PA and FA were viewed as the company's best chance for competing
in the diesel market. ALCo used an all-out publicity campaign
to promote the PA cab units and quickly phased out DL-109 production
once the decision was made to promote the PA as its premier passenger
locomotive. With the introduction of the Model 244 16 cylinder
prime mover, the PA quickly replaced the DL-109 in ALCo's stable
of diesel locomotives.

It should be noted that the unusual circumstances
caused by the Second World War and insurmountable competition
from EMD are what made the DL-109 the obscure cab unit it is,
not inferior performance. During the war, the New Haven used its
DL-109's in around the clock operations, pulling passenger trains
during the daytime and freight trains at night. In addition, it
is interesting to note that the Rock Island rebuilt one its DL-109's
in 1953 with an EMD prime mover and kept the cab unit running
until the late 1950's.

Railfan perspective:

The DL-109 may rank as the most exotic diesel
cab unit, if not the most obscure. Few railfans are even aware
of its existence, and certainly it does not warrant the fanfare
attributed to many of the other early diesel cab units, as it
was not produced in the same quantities as many of its contemporaries.
Nor does its styling set it off as truly unique. It is however,
noteworthy in that it marked the first attempt by one of the world's
greatest manufacturers of steam locomotives to build a streamlined
passenger diesel locomotives at a time when diesel technology
was still relatively primitive. It showed incredible foresight
on the part of ALCo that they were able to recognize at an early
stage of diesel development that Baldwin and Lima Locomotive Works
were no longer its only competition and that EMD was becoming
a force in the diesel traction market.